Disclosed are embodiments for determining a location of a wireless terminal. The wireless terminal measures signal strength of a plurality of wireless transmitters. Based on this information, a plurality of location probability surfaces are generated. Each location probability surface indicates a plurality of probabilities that the wireless terminal is in each of a corresponding plurality of geographic regions. These probability surfaces are then averaged to determine a composite location probability surface. A motion probability surface is also determined, which stores a plurality of probabilities indicating variations of motion of the wireless terminal. The composite location probability surface is then updated based on the motion probability surface. A location estimate of the wireless terminal is then determined based on the updated composite location probability surface.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A system, comprising: hardware processing circuitry; one or more hardware memories storing instructions that when executed configure the hardware processing circuitry to perform operations comprising: receiving, from a wireless terminal, a signal strength measurement of a signal received by the wireless terminal, the signal generated by a first wireless transmitter; determining, for each of a plurality of regions, an expected signal strength of the signal from the wireless transmitter in the respective region; determining, for each of the plurality of regions, a corresponding first difference between the expected signal strength in the respective region and the signal strength measurement; determining, for each of the plurality of regions, a corresponding first probability that the wireless terminal is located in the respective region based on one of the first differences that corresponds to the respective region; receiving acceleration information from the wireless terminal: generating a plurality of motion estimates of the wireless terminal based on the acceleration information; generating associated motion probabilities for the plurality of motion estimates; generating a predicted location probability surface, the generating of the predicted location probability surface comprising for each of the plurality of regions, generating a third probability that the wireless terminal is located in the respective region based on the plurality of motion estimates and the associated motion probabilities, wherein the predicted location probability surface is generated to indicate each of the third probabilities; and estimating a first location of the wireless terminal at a first time based on the determined first probabilities and the predicted location probability surface.
2. The system of claim 1 , wherein each of the regions of the plurality of regions represents a two-dimensional geographic area or a three-dimensional geographic volume.
3. The system of claim 1 , the operations further comprising: receiving, from the wireless terminal, a second signal strength measurement of a second signal received by the wireless terminal and generated by a second wireless transmitter; determining, for each of the plurality of regions, a corresponding second expected signal strength of the signal from the second wireless transmitter in the respective region; determining, for each of the plurality of regions, a corresponding second difference between the second expected signal strength in the respective region, and the second signal strength measurement; determining, for each of the plurality of regions, a corresponding second probability that the wireless terminal is located in the respective region based on one of the second differences that corresponds to the respective region, wherein the estimating of the first location of the wireless terminal is further based on the determined second probabilities.
4. The system of claim 3 , the operations further comprising: aggregating, for each of the plurality of regions, the first probability and the second probability that correspond to the respective region, wherein the estimating of the first location is based on the aggregating.
5. The system of claim 1 , wherein the generating of a third probability comprises determining, for each of the motion estimates, a resulting region in which the wireless terminal is located by exhibiting motion according to the respective motion estimate; aggregating probabilities associated with motion estimates having equivalent resulting regions, wherein the third probability of a region is the aggregated probability of the region.
6. The system of claim 1 , wherein the motion probabilities are generated in accordance with a predetermined distribution.
7. The system of claim 4 , the operations further comprising generating a first blended probability surface based on the predicted location probability surface and the aggregation of the first probability and the second probability, wherein the estimating of the first location is based on the first blended probability surface.
8. The system of claim 7 , the operations further comprising estimating a second location of the wireless terminal at a second time earlier than the first time, the estimating based on a second blended location probability surface, wherein the predicted location probability surface is based on the second blended probability surface.
9. The system of claim 8 , wherein the plurality of motion estimates are determined at the second time, and the predicted location probability surface indicates probabilities that the wireless terminal is located in each of the plurality of regions at the first time.
10. The system of claim 8 , wherein the generating of the plurality of motion estimates is further based on a third blended location probability surface; and the operations further comprise estimating a third location of the wireless terminal at a time earlier than the second time, the estimating of the third location based on the third blended location probability surface.
11. The system of claim 7 , the operations further comprising determining a region with a largest probability in the first blended probability surface, wherein the estimating of the first location estimates the wireless terminal's location as a region associated with a largest probability indicated by the first blended probability surface.
12. The system of claim 7 , the operations further comprising identifying a predetermined number of regions represented by the first blended probability surface that have higher probabilities than other regions, wherein the estimating of the first location is based on a weighted average that is based on the identified regions and excludes the other regions.
13. The system of claim 12 , the operations further comprising weighting each identified region based on its associated probability, wherein the estimating of the first location is based on the weight of each identified region.
14. The system of claim 7 , wherein the generating of the first blended location probability surface comprises averaging corresponding probabilities in the predicted location probability surface and the aggregation of the first probability and the second probability.
15. The system of claim 14 , wherein the averaging of the corresponding probabilities is a weighted average.
16. A method of estimating a location of a wireless terminal, comprising: receiving acceleration measurements representing motion of the wireless terminal at a first time; estimating a location of the wireless terminal at the first time based on a first blended location probability surface, the first blended location probability surface indicating a plurality of probabilities that the wireless terminal is located, at the first time, in a corresponding plurality of geographic regions; generating a predicted location probability surface of the wireless terminal based on the acceleration measurements and the first blended location probability surface, the predicted location probability surface indicating a second plurality of probabilities that the wireless terminal is located, at a second time subsequent to the first time, in the corresponding plurality of geographic regions; aggregating a plurality of location probability surfaces, each location probability surface based on a signal strength at the wireless terminal of a different wireless transmitter, each location probability surface indicating a third plurality of probabilities that the wireless terminal is located, at the second time, in the corresponding plurality of geographic regions, the aggregation generating a composite location probability surface; generating a second blended location probability surface based on the predicted location probability surface and the composite location probability surface; and estimating a second location of the wireless terminal at the second time based on the second blended location probability surface.
17. The method of claim 16 , further comprising generating each of the plurality of location probability surfaces by: generating an expected signal strength of the respective wireless transmitter in each of the plurality of regions, determining, for each region, a difference between the expected signal strength in the respective region and the signal strength of the respective wireless transmitter at the wireless terminal; and generating, for each region, a probability that the wireless terminal is located in the respective region based on the difference.
18. The method of claim 16 , wherein the estimating of the second location of the wireless terminal at the second time is based on a second blended location probability surface, the method further comprising: estimating a third location of the wireless terminal at a time earlier than the first time based on a third blended probability surface; generating motion estimates and associated probabilities of the wireless terminal based on the third blended probability surface and the acceleration measurements, wherein the generation of the predicted location probability surface is further based on the generated motion estimates and associated probabilities.
19. The method of claim 16 , further comprising determining, during each of a plurality of periodic time periods: a motion surface, the motion surface defining a plurality of probabilities that the wireless terminal exhibited a plurality of corresponding motion parameters during the respective periodic time period, and a plurality of location surfaces, each location surface defining a plurality of probabilities that the wireless terminal is located, during the respective time period, in a corresponding plurality of regions, the plurality of location surfaces including: a plurality of location probability surfaces, each location probability surface based on signals received at a different device, a composite location probability surface, the composite location probability surface aggregating corresponding probabilities of the plurality of location probability surfaces, a predicted location probability surface, wherein the predicted location probability surface defines the plurality of probabilities that the wireless terminal is located, in a next time period, in the corresponding regions, the predicted location probability surface based on the motion surface of the respective time period and a blended location probability surface of a previous time period, and the blended location probability surface, the blended location probability surface based on the predicted location probability surface and the composite location probability surface.
20. A non-transitory computer readable storage medium comprising instructions that when executed configure hardware processing circuitry to perform operations to estimate a location of a wireless terminal, the operations comprising: receiving acceleration measurements representing motion of the wireless terminal at a first time; estimating a location of the wireless terminal at the first time based on a first blended location probability surface, the first blended location probability surface indicating a plurality of probabilities that the wireless terminal is located, at the first time, in a corresponding plurality of geographic regions; generating a predicted location probability surface of the wireless terminal based on the acceleration measurements and the first blended location probability surface, the predicted location probability surface indicating a second plurality of probabilities that the wireless terminal is located, at a second time subsequent to the first time, in the corresponding plurality of geographic regions; aggregating a plurality of location probability surfaces, each location probability surface based on a signal strength at the wireless terminal of a different wireless transmitter, each location probability surface indicating a third plurality of probabilities that the wireless terminal is located, at the second time, in the corresponding plurality of geographic regions, the aggregation generating a composite location probability surface; generating a second blended location probability surface based on the predicted location probability surface and the composite location probability surface; and estimating a second location of the wireless terminal at the second time based on the second blended location probability surface.
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February 28, 2020
April 13, 2021
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